Shell or cartridge case



Patented Got. 7, 1924.

NET

FRANK A. FAHRENWALD, 0F CLEVELAND HEIGHTS, OHIO.

SHELL OR CARTRIDGE CASE.

No Drawing.

To all whom it may concern:

Be it known that I, FRANK A. F AHREN- WALD, a citizen of the United States, residing at Cleveland Heights, in the county of Cuyahoga and State of Ohio, have. invented a certain new and useful Improvement in Shell or Oartridge Cases, of which the following is a full, clear, and exact description. This invention relates to an improvement in cartridge cases and primers for use in ordnance or the manufacture of sporting or military cartridges. In small sized arms the loading unit is called a cartridge and consists of a powder container having a charge of propellant therein, a projectile or bullet in one end and a fulminating charge in the other end; in the smallest cartridges the latter is frequently spread over the bottom of the powder container and penetrates into a fold around the base of the same, being exploded by a blow upon the rim, whence arises the name rim-fire cartridges; in the larger sizes the fulminate is contained in a separate member called the primer, used in the base of the powder container generally at the center, wherefore these are called center-fire cartridges. In

these small sized units, the powder con-.

tainer is called a shell and has hitherto been made of copper for the smallest arms, brass for the medium and high powered rifles, and of brass and paper for shot-guns. In small ordnance the loading unit ordinarily employed is of the same description as the center fire rifle cartridge, except that the term shell is applied to the projectile instead of to the powder container, the latter being ordinarily made of brass. In large ordnance, the projectile is handled and inserted independently. of the propellant, the latter being ordinarily contained in fabric bags.

The present invention relates to the powder-container (and also to the primer incase oneis used) and to this part or combination of parts I-apply the term cartridge case, intending thereby to include both powder container and primer (in cases where the latter is a separate part) regardless of the size of arm and regardless of whether one bullet or many be employed and whether the same be aflixed in or to such cartridge case or be handled separately. The metals and alloys heretofore used for these parts suffer the defects of great weight, high intrinsic value, and sus- Application filed February 26, 1920. Serial No. 361,394.

ceptibility to corrosion. The first of these serves to limit unduly the labor of carrying an adequate supply of ammunition, the second renders the ammunition unduly expen sive, and the third impedes or prevents reloading and sometimes renders difficult the extraction of the cartridge case after firing' The objects of my invention are the provision of a cartridge case which is not affected by ordinary atmospheric influences, by powder residues. or by salt solutions encountered in actual practice such as sea water and perspiration; the provision of a cartridge casing of less weight than the ordinary one of brass or copper, and which is of lower intrinsic value; the provision of shell material whose cost of manufacture, due to the greater ductility of the alloy and the lower temperatures required for working and annealing during drawing operations, will also be substantially lower; while further objects and advantages. of the invention will appear as the description proceeds.

The essence of my invention consists in the employment of alloys composed chiefly v of aluminum together with smaller quantities of hardening and toughening materials, principally copper and magnesium. Silicon has a desirable effect when present to not over about 5 and the hardness and elasticity of the alloy are greatly increased by the addition of small amounts of manganese, chromium or iron group metals. The use of zinc or similar metals, however, renders the alloy so easily fusible and so lowers the annealing temperature that its use is not desirable. Iron, manganese, or nickel may be employed up to about two per cent, although I prefer to keep them below about one per cent. I have added copper up to about eight per cent and magnesium up to about twelve per cent without causing the alloy to become sohard that it could not be worked into the desired shapes. I prefer, however, to keep the copper between about one-half per cent and six per cent and the magnesium below about six per cent, and themore refractory metals below about 1.5 per cent. I have found that. it is practically impossible to add more than about fifteen per cent of all alloying constituents combined without destroying the properties of these aluminum alloys for cartridge case purposes, other elements such as molybdenum, tungsten, vanadium, titanium, etc., may be used in small amounts without detriment and even with beneficial I the smaller size shells when the same consists of one or more of the substances, magnesium, silicon, iron, manganese, nickel, molybdenum. tungsten, vanadium, or titanium and eighty five per cent of aluminum alloyed with eight per cent of magnesium, five per cent of copper, two per cent manganese copper, iron and silicon or iron-group metals, etc. It is desirable, however. to employ limits less' extensive than these, especially the upper limits of hardening materials. My preferred alloy consists of Iron and s1l1con or Different types of cartridge cases require different grades of alloys, however, so it is necessary to vary the composition to meet these requirements. It is essential, for instance, to employ a much softer alloy for rim-fire cartridges than for those which are equipped with a cap. In this" case the fulminate is fired by being compressed between inner surfaces of the fold which'forms the head of the shell. When as in this case, a softer and tougher alloy is required, the amount ofhardening and toughening constituents may be materially reduced. A similar effect may be brought about by suitably annealing after all drawing and formingoperations are completed.

iron-group metals. 0.6%

. For certain sporting and military cartridges, however, it IS necessary to increase the amount of hardening and toughening constituents, and to form the shell with the least required amount of annealing in order to produce a shell in which the material has been subjected to the greatest possible amount of cold work with its resulting high values for tensile strength and elasticity.

It is also possible to improve the qualities of these alloys by a suitable heat treatment, and for certain requirements the properties so produced are essential. This treatment consists in subjecting the alloy to a temperature between 450 to 550 and then quenching in some suitable medium at a temperature which varies with the grade of alloy.

In the cold worked condition some of the above described alloys possess a tensile strength upward of seventy thousand pounds per square inch which is far above that required in most cartridge cases.

The above described alloys are particularly adapted to the manufacture of rifle and pistol cartridges from the small twentytwo caliber tothe more powerful high velocity type, although shotgun shells and larger cases for ordnance may be made of this alloy with great satisfaction. Owing to the very low specific weight of aluminum, a given case of this material costs less than a similar case of brass despite the higher cost of aluminum per pound. Likewise, the extremely light weight of the alloy de creases the total weight of the loaded cartridge to a remarkable extent, in many instances connected with military cartridges as much as one-third, thereby enabling a soldier to carry a fifty per cent increased supply of ammunition with the same labor. Furthermore, this material remains bright and untarnished almost indefinitely when subjected to salt solutions, atmospheric conditions, or even to powder gases and residues, as a result of which it neither becomes fouled in carrying or sticks in the firing chamber. Its elasticity is such as to cause it to return to its original size after each firing notwithstanding the instantaneous' expansion by the powder gases, thus avoiding extraction difficulties and render ing reloading possible. Its low cost renders it feasible for use in shot gun shells and in powder containers for heavy ordnance. It is without chemical action on propellants or fulminates. It can be drawn and worked with the greatest ease. In the case of certain extremely high-velocity sporting or military cartridges of the so-called rimless -type, I have found it advisable to support the base of the shell of the case with a cup or ring of some harder or stiffer material such as steel or bronze to prevent crushing and I lay claim to such composite cartridge cases as a part of my invention which fall within the annexed claim.

Having thus described my invention, what I claim is:

I A cartridge case made from an alloy containing approximately, 95.5% aluminum, 1.5% copper, 2.0% magnesium, 1.0% a metal adjacent to iron in the periodic table.

In testimony whereof, I hereunto afiix my signature.

. FRANK A. FAHRENWALD. 

